Small grass yellow butterflies feed on fresh elephant dung in Kenya’s Tsavo West National Park.

Photograph by Nigel Pavitt, Getty

Butterflies have had us fooled for centuries. They bobble around our gardens, all flappy and floppy, looking so pretty with their shimmering colors. We even write odes to them:

Thou spark of life that wavest wings of gold,Thou songless wanderer mid the songful birds,With Nature’s secrets in thy tints unrolledThrough gorgeous cipher, past the reach of words,Yet dear to every childIn glad pursuit beguiled,Living his unspoiled days mid flowers and flocks and herds!—Ode To A Butterfly, by Thomas Wentworth Higginson

But butterflies have a dark side. For one thing, those gorgeous colors: They’re often a warning. And that’s just the beginning. All this time, butterflies been living secret lives that most of us never notice.

Take this zebra longwing, Heliconius charithonia. It looks innocent enough.

The zebra longwing butterfly was made Florida’s state butterfly in 1996.

Pixabay, CC0

But it’s also famously poisonous, and its caterpillars are cannibals that eat their siblings. And that’s hardly shocking compared with its propensity for something called pupal rape.

Once you know that a pupa is the butterfly in its chrysalis—in between being a larva and an adult—then pupal rape is pretty much what it sounds like. As a female gets ready to emerge from her chrysalis, a gang of males swarms around her, jostling and flapping wings to push each other aside. The winner of this tussle mates with the female, but he’s often so eager to do so that he uses his sharp claspers to rip into the chrysalis and mate with her before she even emerges.

Since the female is trapped in the chrysalis and has no choice in the matter, the term pupal rape came about, though some biologists refer to it more charitably as “forced copulation” or simply pupal mating. Whatever you call it, it’s hardly the stuff of children’s books.

And don’t think for a minute that zebra longwings are an anomaly—plenty of their kin are bad boys, too.

One day in Kenya’s North Nandi forest, Dino Martins, an entomologist, watched a spectacular battle between two white-barred Charaxes. A fallen log was oozing fermenting sap, and while a fluffy pile of butterflies was sipping and slowly getting drunk, the two white-barred butterflies showed up and started a bar fight. Spiraling and slicing at one another with serrated wings, the fight ended with the loser’s shredded wings fluttering gently to the forest floor.

A green-veined Charaxes dines on animal poop.

Photograph by Dino Martins

Martins, a former National Geographic Emerging Explorer, wrote about Charaxes, or emperor butterflies, in Swara magazine, published in East Africa where he is now Director of Kenya’s Mpala Research Centre.

“They are fast and powerful,” he writes. “And their tastes run to stronger stuff than nectar: fermenting sap, fresh dung and rotting carrion are all particular favourites.”

That’s right; don’t get between a butterfly and a freshly dropped pile of dung. It drives them wild. They uncoil their probosces and slurp away, lapping up the salts and amino acids they can’t get from plants.

Sorry, kids—not always. Butterflies start life as caterpillars, which are far from harmless if you’re a tasty plant, and can be carnivorous. Some are even parasites: Maculinea rebeli butterflies trick ants into raising their young. The caterpillars make sounds that mimic queen ants, which pick them up and carry them into their colonies like the well-to-do being toted in sedan chairs. Inside, they are literally treated as royalty, with worker ants regurgitating meals to them and nurse ants occasionally sacrificing ant babies to feed them when food is scarce. Butterflies invented the ultimate babysitting con.

Yes, moths are also known to “mud puddle,” also to get salts and minerals in their diet. And an interesting fact: if you see a bunch of butterflies mud puddling, often most of them are males. Scientists think this is probably because females get salts from the male, in a spermatophore package, when they mate.

missed out the gory details of blood drinking moths (Calpe spp., Erebidae).
also worth thinking about butterflies (and moths) “mud puddling” in certain patches only – just like solid output, these “puddles” often contain urine, thus attract the butterflies due to chemical content….

I’ve also seen male Tiger Swallowtail butterflies act territorial around my butterfly bush. If another male Swallowtail comes up, or some other butterfly specimen, the Swallowtail there will chase him or her away from the bush. I remember one time, our bush was swarming with Painted Lady butterflies. After watching them for a while, I went inside for a bit, and then when I returned outside, the Painted Ladies were gone and there was a single male Tiger Swallowtail butterfly flitting around the bush. The Swallowtail probably wasn’t happy about the Painted Ladies swarming on the bush he was to feed at.
Now, if a female TIger Swallowtail butterfly comes to the bush while a male is there, it’s another story…

About Erika

Erika Engelhaupt is senior editor for blogs at National Geographic. In her blog Gory Details, she delves into the bizarre and fascinating world of science.

Her work has also appeared in Science News, NPR, the Philadelphia Inquirer, Story Collider, Environmental Science & Technology, and other magazines and newspapers. She lives in the eerie world of Washington, D.C.

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Phenomena is a gathering of spirited science writers who take delight in the new, the strange, the beautiful and awe-inspiring details of our world. Phenomena is hosted by National Geographic magazine, which invites you to join the conversation. Follow on Twitter at @natgeoscience.